Night Owls

As we grow up our sleep behavior changes. In our teens, we need lots of sleep and getting us out of bed in the mornings is not an easy task. This is not made any easier by the tendency of the young to be semi-nocturnal – a habit that can last until they should all know better. Of course, way back in our evolutionary infancy, we were nocturnal little primates doing our best not to get swallowed up by the large predatory beasts out there.

As the ancestral primates of 50 to 60 Myr ago came out of the dark, they developed a wide range of social structures running the gamut of solitary individuals through single male polygamous groups to large social groups. There have been a couple of theories as to how the social groups developed. Shultz and her colleagues have published the results of a computer simulation that seems to fit the bill better than previous pictures (1).

The benefits of daytime foraging are counterbalanced by the increased risk of being spotted and ending up as someone else’s breakfast.   The simulation predicts that the predation risk would be lessened by loose aggregates of the emerging primates. Further cohesion into large cooperative social groups would further enhance this benefit.

Better foraging results and better protection against predation then leads to more babies and expanding populations. So it seems that social living resulted from giving up the night shift and didn’t appear to have anything to do with looking around for sexual partners.

It seems somewhat ironic that after almost 20 Myr of evolution, our younger generation should seem to be so in love with the nocturnal lifestyle.


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